algorithms on visual basic

Currently I have a simulation model which shows patients waiting in a queue. This model has a visual basic interface. The selections are made on this interface, and then the model is run based upon the selected criteria. At the moment on this vb interface, only one selection can be made for priortising the patients. I need to allow more than one selection to be made at one time. Therefore, I need to develop multi selection method/algorithm into the current code for this particular form. ## Deliverables Fully working code, and model to run accordingly to ensure code is correct. ## Platform Windows XP. Simulation software would also be an advantage, but not neccessary.